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Biomedical subjects

L Wang

Publications and source records attributed to L Wang.

At least 523 records · Page 29Linked to original sources
PubMed2001

[Laser Doppler imaging and cryoglobulinemia].

Continuous microcirculation monitoring of the right foot was carried out for the first time in a 62-year-old patient with cryoglobulinaemia prior to, during and after manual needle insertion at Jie Xi(St.41) acupuncture point using a new method of laser Doppler perfusion imaging (PIMII, Lisca AB, Linköping, Sweden). In addition to visual inspection, changes in mean perfusion were also used as evaluation parameters. Our results suggest that the new biomedical technique of laser Doppler imaging is a useful method for monitoring the effects of acupuncture on the peripheral microcirculation.

Acupuncture Therapy↗
PubMed2001

Quantitative structure-activity relationships: comparative inhibition of nitrogen-containing aromatics on germination of Cucumis sativus.

Comparative inhibition effect of selected nitrogen-containing aromatics on germination rate of Cucumis sativus was investigated, and quantitative structure-activity relationships were developed and mechanistically interpreted. Energy of lowest unoccupied orbital was found to successfully model the toxicity of the test chemicals. It was discovered that inhibition of nitrogen-containing aromatics to germination of Cucumis sativus was caused mainly by their in vivo redox reaction.

Aminopyridines↗
PubMed2001

How does HIV cause depletion of CD4 lymphocytes? A mechanism involving virus signaling through its cellular receptors.

HIV infection causes an acquired immunodeficiency, principally because of depletion of CD4 lymphocytes. The mechanism by which the virus depletes these cells, however, is not clearly understood. Since the virus predominantly infects CD4 lymphocytes in vivo, some have assumed that HIV replication directly kills the infected cells or that the anti-HIV immune response destroys them. However, a large number of studies do not support this concept. Rather, the data strongly indicate that CD4 lymphocyte depletion is by an indirect mechanism. Several theories on various direct and indirect mechanisms are reviewed. The most plausible mechanism, which is backed by in vivo data, involves the consequences of HIV contact with resting CD4 lymphocytes, which cannot support virus replication. HIV binding to, and signaling through, CD4 and chemokine receptor molecules on resting CD4 lymphocytes and other cell types [which extensively occurs as the rare, productively infected cells (ie: infected cells producing virus) migrate among other cells through the lymphoid tissues back into the blood] induces upregulation of L-selectin and Fas. When these resting, HIV-signaled CD4 cells return to the blood, they home very rapidly back to peripheral lymph nodes and axial bone marrow, and their disappearance from the blood is likely due to their leaving the circulatory system. Approximately one-half of these cells that have been induced by HIV to home to lymph nodes are subsequently induced into apoptosis during the process of trans-endothelial migration when secondary signals are received through various homing receptors. These cells are not making HIV, which would explain the observation that CD4 cells not making HIV are the predominant cells dying in the lymph nodes of HIV+ subjects. These studies indicate that the principal mechanism of CD4 T-cell depletion by HIV is due to its use of CD4 as its primary receptor and the signaling induced through this receptor on nonpermissive (resting) T-lymphocytes. This unique mechanism of viral pathogenesis, if correct, leads to the possibility that HIV might not cause depletion of CD4 lymphocytes if it used some other receptor to infect CD4 lymphocytes.

CD4-Positive T-Lymphocytes↗
PubMed2001

Phenotypic and genotypic characterization of Pseudomonas fluorescens isolated from bulk tank milk.

Pseudomonas fluorescens isolates (n = 55) isolated from farm bulk tank milk (n = 55) from dairy herds in eastern South Dakota and western Minnesota were examined for phenotypic (biotype, proteolytic, and lipolytic profiles) and genotypic (plasmid profiles and 16S-23S PCR ribotypes) characteristics. The observed phenotypic and genotypic characteristics were used to conduct phylogenetic analysis. Pseudomonas fluorescens belonged to 28 API 20 NE biotypes and 14 proteolytic and lipolytic profiles. It was observed that 80, 91, and 58% of the isolates were proteolytic at 7, 22, and 32 degrees C, respectively. Only 7, 44, and 7% of the isolates were lipolytic at the same three temperatures. Pseudomonas fluorescens was more likely to produce proteinases at 7 and 22 degrees C and lipases at 22 degrees C. Only 9 of 55 isolates of P. fluorescens harbored plasmids. This small percentage of plasmid-bearing isolates provided insufficient data for inferences related to the distribution of plasmid-bearing clonal types. Based on 16S-23S PCR ribotyping, P. fluorescens belonged to 14 subtypes. The 16S-23S PCR ribotyping technique allowed differentiation between strains; however, it did not concur with the biotypes and proteolytic and lipolytic profiles. Use of biotypes in conjunction with proteolytic and lipolytic profiles might have practical value for conducting trace-back studies related to P. fluorescens. Based on phylogenetic analysis, it was inferred that for the given geographical area and time period, P. fluorescens isolated from farm bulk tank milk consists of a large heterogeneous group of organisms.

Animals↗
PubMed2001

Identification of Candida dubliniensis based on the specific amplification of mitochondrial cytochrome b gene.

Candida dubliniensis, a recently described Candida species, is frequently isolated from oral candidiasis in human immunodeficiency virus infected individuals. To detect the organism rapidly, we have developed specific oligonucleotide primers based on the sequences of mitochondrial cytochrome b gene. These primers selectively amplified DNA only from C. dubliniensis; the DNAs of all pathogenic Candida species tested, as well as those of medically relevant yeasts such as Cryptococcus neoformans, and Trichosporon cutaneum, were not amplified. This is the first report describing the effectiveness of cytochrome b gene in PCR based detection of an organism, and we hope the system will be useful as a microbiological tool for rapid detection of C. dubliniensis.

Base Sequence↗
PubMed2001

Metastatic human hepatocellular carcinoma models in nude mice and cell line with metastatic potential.

Metastatic human HCC model is needed for the studies on mechanism and intervention of metastatic recurrence. By using orthotopic implantation of histologically intact tissues of 30 surgical specimens, a patient-like metastatic model of human HCC in nude mice (LCI-D20) and a low metastatic model of human HCC in nude mice (LCI-D35) have been established. All mice with transplanted LCI-D20 tumors exhibited extremely high metastatic ability including spontaneous metastasis to liver, lungs, lymph nodes and peritoneal seeding. Remarkable difference was also found in expression of some of the invasiveness related genes and growth factors between the LCI-D20 and LCI-D35 tumors. PAI-1 increased gradually following tumor progression in LCI-D20 model, and correlated with tumor size and AFP level. Phasic expression of tissue intercellular adhesion molecule-1 in this model was also observed. Using corneal micropocket model, it was demonstrated that the vascular response induced by LCI-D20 tumor was stronger than that induced by LCI-D35 tumor. Similar report on metastatic human HCC model in nude mice and human HCC cell line with metastatic potential was rarely found in the literature. This LCI-D20 model has been widely used for the studies on intervention of metastasis, including anti-angiogenesis,antisense approach, metalloproteinase inhibitor, differentiation inducer, etc. It is concluded that the establishment of metastatic human HCC model in nude mice and human HCC cell line with metastatic potential will provide important models for the in vitro and in vitro study of HCC invasiveness, angiogenesis as well as intervention of HCC recurrence.

Animals↗
PubMed2001

Apoptosis, proliferation and p53 gene expression of H. pylori associated gastric epithelial lesions.

AIM: To study the relationship between Helicobacter pylori (H. pylori) and gastric carcinoma and its possible pathogenesis by H. pylori. METHODS: DNEL technique and immunohistochemical technique were used to study the state of apoptosis, proliferation and p53 gene expression. A total of 100 gastric mucosal biopsy specimens, including 20 normal mucosa, 30 H. pylori-negative and 30 H. pylori-positive gastric precancerous lesions along with 20 gastric carcinomas were studied. RESULTS: There were several apoptotic cells in the superficial epithelium and a few proliferative cells within the neck of gastric glands, and no p53 protein expression in normal mucosa. In gastric carcinoma, there were few apoptotic cells, while there were a large number of proliferative cells, and expression of p53 protein significantly was increased. In the phase of metaplasia, the apoptotic index (AI, 4.36%+/-1.95%), proliferative index (PI, 19.11%+/-6.79%) and positivity of p53 expression (46.7%) in H. pylori-positive group were higher than those in normal mucosa (P<0.01). AI in H. pylori-positive group was higher than that in H. pylori-negative group (3.81%+/-1.76%), PI in H. pylori-positive group was higher than that in H. pylori-negative group (12.25%+/-5.63%, P<0.01). In the phase of dysplasia, AI (2.31%+/-1.10%) in H. pylori-positive group was lower (3.05%+/-1.29%) than that in H. pylori-negative group, but PI (33.89%+/-11.65%) was significantly higher (22.09+/-8018%, P<0.01). In phases of metaplasia, dysplasia and gastric cancer in the H. pylori-positive group, AIs had an evidently graduall decreasing trend (P<0.01), while PIs had an evidently gradual increasing trend (P<0.05 or P<0.01), and there was also a trend of gradual increase in the expression of p53 gene. CONCLUSION: In the course of the formation of gastric carcinoma, proliferation of gastric mucosa can be greatly increased by H. pylori, and H. pylori can induce apoptosis in the phase of metaplasia, but in the phase of dysplasia H. pylori can inhibit cellular apoptosis. And H. pylori infection can strengthen the expression of mutated p53 gene.

Apoptosis↗
PubMed2001

Role of calcium-dependent protease(s) in globulization of isolated rat lens cortical fiber cells.

PURPOSE: To investigate the role of calcium-activated proteases in calcium-dependent disintegrative globulization of isolated rat lens cortex fiber cells. METHODS: Rat lens fiber cells were isolated and plated on coverslips at the bottom of a temperature-controlled chamber. The fiber cells were incubated with 10 microM protease substrate, (t-butoxycarbonyl-leu-met-7-amino-4-chloromethylcoumarin:BOC-Leu-M et- CMAC) and the proteolytic activity in the fiber cells was determined by observing the increase in fluorescence, using an excitation wavelength of 360 nm, and measuring emission at 410 nm. Free intracellular calcium was measured using the cell-permeable calcium indicator Fluo-3-AM, and the globulization time (T(g)) was determined using image analysis. RESULTS: T:(g) of fiber cells superfused with Ringer's solution containing 2 x 10(-)(3) M, 10(-)(6) M, and 10(-)(8) M [Ca(2+)](o) were: 24.7 +/- 1.3, 53.0 +/- 2.8, and more than 120 minutes, respectively. A significant increase in T:(g) ( approximately 95 minutes) was observed when the fibers were preincubated with acetoxymethyl ester of 1,2-bis (2-amino-phenoxy) ethane N:, N:, N:, N:-tetra-acetic acid (BAPTA-AM) to buffer changes in [Ca(2+)](i), or the protease substrate to competitively inhibit degradation of cellular proteins. In the presence of Ringer's solution containing 2 x 10(-)(3) M [Ca(2+)](o) and 0.5 mM of the cysteine protease inhibitor, leupeptin, T:(g) increased to 100 minutes, without affecting [Ca(2+)](i). The proteolytic activity of fiber cells in Ringer's solution containing 10(-)(6) M and 2 x 10(-)(3) M [Ca(2+)](o) increased by approximately 7- and 12-fold, respectively, compared with sucrose-EDTA solution or Ringer's solution containing 10(-)(8) M [Ca(2+)](o). This increase in proteolytic activity was inhibited by leupeptin. CONCLUSIONS: Elevation of calcium in the medium results in a proportionate increase in [Ca(2+)](i) and the proteolytic activity in isolated lens fiber cells. The increase in the proteolytic activity is accompanied by an increase in the rate of globulization of the fiber cells. Inhibition of the proteolytic activity by leupeptin increases T:(g) without affecting the gain in [Ca(2+)](i). These results suggest that globulization of isolated fiber cells in physiological salt solutions is mediated by Ca(2+)-activated protease(s).

Aniline Compounds↗
PubMed2001

Keratin 23 (K23), a novel acidic keratin, is highly induced by histone deacetylase inhibitors during differentiation of pancreatic cancer cells.

Sodium butyrate (NaBu) was shown to induce differentiation and apoptosis in the human pancreatic cancer cell line AsPC-1. A suppression subtractive hybridization-based technique was used to identify genes induced by NaBu. A novel cDNA was found to be highly up-regulated in AsPC-1 cells in response to NaBu. The gene expresses a 1.65-kb mRNA encoding a protein with an open reading frame of 422 amino acids. It has an intermediate filament signature sequence and extensive homology to type I keratins. Sequence comparison with known keratins indicated that the gene shares 42-46% amino acid identity and 60-65% similarity within the alpha-helical rod domain. The gene is named K23 (for human type I Keratin 23, KRT23). K23 mRNA was highly induced by NaBu in different pancreatic cancer cells. Trichostatin A (TSA), a potent and specific inhibitor of histone deacetylase, similarly induced K23 mRNA expression. Treatment with either actinomycin D or cycloheximide efficiently blocked the induction of K23 mRNA by NaBu/TSA. These results indicate that K23 mRNA induction by NaBu or TSA is a downstream event of histone hyperacetylation. We also demonstrated that expression of p21(WAF1/CIP1) antisense RNA efficiently blocked the induction of K23 mRNA induced by NaBu. Our results suggest that K23 is a novel member of the acidic keratin family that is induced in pancreatic cancer cells undergoing differentiation by a mechanism involving histone hyperacetylation. p21(WAF1/CIP1) serves as an important mediator during the induction process of K23 by NaBu.

Acetylation↗
PubMed2001

Nerve growth factor exerts differential effects on the growth of human pancreatic cancer cells.

Nerve growth factor (NGF) exerts both stimulatory and inhibitory effects on neuronal and certain nonneuronal tumors with the effect based on the type of tumor. We investigated NGF and its receptors (TrkA and p75) in pancreatic cancer cells (PANC-1, MIA-PaCa-2, CAPAN-1, ASPC-1, and T3M4) by reverse transcription-PCR, Western blot analysis, NGF ELISA, and growth assays. NGF mRNA was present at comparable levels in all five pancreatic cancer cell lines. TrkA expression was relatively high in PANC-1 and MIA-PaCa-2 cells and low in CAPAN-1, ASPC-1, and T3M4 cells. p75 expression was high in PANC-1, MIA-PaCa-2, and T3M4 cells, moderate in CAPAN-1, and low in ASPC-1 cells. By ELISA assay, the intracellular NGF content in all cell lines was approximately 40 pg/10(6) cells. NGF content increased significantly in PANC-1 and MIA-PaCa-2 cells when these cells were cultured with serum-free media, whereas there was no change in the other cancer cell lines. PANC-1 and MIA-PaCa-2 cells but not the other cell lines released NGF in the culture media. Exogenous NGF stimulated the growth of PANC-1 and MIA-PaCa-2 cells, inhibited the growth of T3M4 and CAPAN-1 cells in a dose- and time-dependent manner, and did not affect the growth of ASPC-1 cells. NGF led to the phosphorylation of TrkA, mitogen-activated protein kinase (MAPK), and p38 MAPK but not stress-activated protein kinase/c-Jun NH2-terminal kinase in PANC-1 and MIA-PaCa-2 cells. In contrast, in the other pancreatic cancer cell lines none of these kinases were phosphorylated by NGF. In conclusion, the effects of NGF on pancreatic cancer cell growth are dependent on the expression levels and the balance of its TrkA and p75 receptors. NGF-induced pancreatic cancer cell growth seems to be mediated through the phosphorylation of TrkA and subsequently via MAPK. These results point to a previously unknown autocrine/paracrine pathway in pancreatic cancer, suggesting that NGF-TrkA interactions are important factors influencing cell growth and spread in this malignancy.

Blotting, Western↗
PubMed2001

Identification and characterization of a novel OCA-B isoform. implications for a role in B cell signaling pathways.

OCA-B is a B lymphocyte-specific transcription coactivator that mediates tissue- and stage-restricted transcription of immunoglobulin genes. Earlier genetic studies revealed that OCA-B is essential for germinal center formation and production of secondary immunoglobulin isotypes. Biochemically purified OCA-B contains p35 and p34 isoforms, and a further analysis has now revealed that p35 is derived from a newly found isoform, p40. More importantly, it has been found that p35 is myristoylated in vivo and that this leads to dramatic changes (including localization to membrane compartments) in its properties. These results suggest that the p35 isoform of OCA-B has functions distinct from those of the nuclear p34 and that it might be a component of a signaling pathway that is required for late-stage B cell development.

3T3 Cells↗
PubMed2001

Improved laboratory confirmation of heparin-induced thrombocytopenia type II. Time course of antibodies and combination of antigen and biologic assays.

We studied whether laboratory confirmation of heparin-induced thrombocytopenia (HIT) can be improved after antigen clearance by determining free antibody and combining the results of an antigenic and a biologic assay. Blood samples taken over 40 days in 14 patients with HIT with thromboembolism underwent fluorescence-linked immunofiltration and the carbon 14-serotonin release assays. Of the 14 patients, 11 showed positive results in both assays at day 1 after stopping heparin. The 3 patients with negative results seroconverted in one or both assays during the subsequent 7 days. Combining the positive results of the assays increased the sensitivity from 85% at day 1 to 100% at day 7. Assay results became negative in all patients within 40 days. The platelet count normalized between days 2 and 9 after withdrawal of heparin. It is assumed that the free antibody can be detected after withdrawal of heparin and after clearance of the platelet factor 4-heparin complex in patients with HIT.

Aged↗
PubMed2001

Saccade initiation and accuracy in gaze shifts are affected by visual stimulus significance.

The effect of visual stimulus significance on saccade latency and accuracy in gaze shifts was investigated. Stimulus significance refers to the temporal proximity of an imperative stimulus. It was hypothesized that stimulus significance serves as a cue that influences the observer's expectancy for a forthcoming event. Twenty-one undergraduate students participated in two experiments involving monitoring of visual events. Stimuli were a sequence of 1,000 single-digit integers presented one at a time at 9 degrees of visual angle to the left or right of a fixation point in random order. The subject was required to make a manual response after the presentation of a sequence of two odd integers. The probability of the subsequent integer being odd, a "target," after the presentation of an odd integer was 0.75. The integer after a target was always an even integer. When stimulus location was unpredictable (Experiment 1), latency of visually guided saccades to the target was shorter (p < .01) than to the nontarget stimuli. Under the condition of predictable stimulus location (Experiment 2), anticipatory saccades to the target occurred earlier (p < .01), more frequently (p < .01), and more accurately (p < .05). Our results suggest that both timing and accuracy of gaze shift are affected by the observer's expectation of future events.

Adult↗
PubMed2001

[Role of metallothionein in the resistance of rat osteoblasts to zinc excess and deficiency].

This study is expected to investigate the role of metallothionein(MT) in the resistance of osteoblasts to high or low zinc conditions. Antisense MT oligonucleotide was used to reduce the content of MT in osteoblast. Cellular MT content was determined by silver/hemolysate saturation method, and the cytotoxicity was measured by the activity of LDH releasing from damaged cells. The results showed that antisense MT oligonucleotide markedly decreased the resistance of osteoblast to zinc excess and zinc deficiency. It suggested that MT played an important role in the modulation and maintenance of intracellular zinc homeostasis of osteoblasts.

Animals↗
PubMed2001

[Improvement of transformation frequency of rice mediated by Agrobacterium].

The factors influencing the frequency of rice transformation mediated by Agrobacterium have been investigated by using 16 commercially important indica and japonica rice cultivars or lines. The main results were as following: For most rice CC medium was the best for both callus initiation and subculture. With supplement of 2.5-5 mg/L ABA the quality of calli can be improved. The concentration of selective agent for Indica rice callus was lower than that for japonica rice callus. Agrobacterium tumefaciens strain EHA105 was more efficient than LBA4404 and AGL1 for rice transformation. The inhibitive effect of cefotaxime to Agrobacterium was better than that of carbenicillin. The partial desiccation treatment after co-cultivation was beneficial to inhibit the growth of Agrobacterium and increase transformation efficiency. A stable and efficient Agrobacterium-mediated transformation system has been established in ten different rice cultivars and fertile transgenic plants have been obtained.

Culture Media↗
PubMed2001

The effects of Lei Gong Teng on reproductive hormones.

The serum reproductive hormone levels were examined with radioimmunoassay in women of child-bearing age before and after treatment with the prescriptions containing Lei Gong Teng ([symbol: see text] Radix Tripterygii Wilfordii). The results showed that Lei Gong Teng could induce amenorrhea, but it was reversible.

Adolescent↗
PubMed2001

[Effects of interferon-alpha on recurrence and metastasis of hepatocellular carcinoma after curative resection in nude mice].

OBJECTIVE: To study the effect of interferon-alpha (IFN-alpha) on the recurrence and metastasis of hepatocellular carcinoma (HCC) in nude mice, and to clarify if there is synergistic effect treated by combination of IFN-alpha and all-trans retinoic acid (ATRA). METHODS: The effect of IFN-alpha and/or ATRA on the proliferation of HCC cell lines was measured in vitro. The metastatic model of human HCC in nude mice LCI-D20 was used in present study. Curative resection was performed at 10th day after implantation in 44 nude mice. Drugs were given at the next day after resection. IFN-alpha was administered subcutaneously at doses of 3+/-10(5) U/day, 6+/-10(5) U/day, respectively. ATRA was administered p.o. at a dose of 20 mg/kg/day, and IFN-alpha 6+/-10(5)U/day combined with ATRA 20 mg/kg/day. The mice were sacrificed 35 days after treatment. The recurrent tumor size was measured and the presence of intrahepatic dissemination and lung metastases were recorded. RESULTS: The effect of IFN-alpha and/or ATRA on the proliferation of HCC cells SMMC7721, BEL-7402, BEL-7405, and MHCC97 was not obvious. The combination of IFN-alpha and ATRA had no synergistic effect in vitro. The lung metastatic rate, the liver recurrent rate, the size of main recurrent lesions, the number of intrahepatic disseminating nodules and the largest disseminating nodule of the controlled group was 100%(12/12), 100%(12/12), (1346.3+/-4.2 ) mm(3), 8.2+/-4.4, 864 mm(3), respectively; whereas it was 0, 87.5%(7/8), (8.7+/-2.9) mm(3), 2.3+/-0.6, and 7.8mm(3), respectively in the IFN-alpha 3+/-10(5) U/day treated group(P<0.05); 0, 12.5%(1/8), 0.5mm(3), 2, 0.5 mm(3) in the IFN-alpha 6+/-10(5)U/day treated group(P<0.05); 0, 12.5%(1/8), 1 mm(3), 2.5+/-0.7, 8 mm(3) in the IFN-alpha 3+/-10(5) U/day and ATRA treated group(P<0.05); 87.5%, 100%, (1472.6+/-5.6) mm(3), 7.3+/-3.8, 768.5 mm(3) in the ATRA treated group (P>0.05). CONCLUSIONS: IFN-alpha has an inhibitory effect on intrahepatic recurrence and lung metastasis of human HCC after curative resection in nude mice, and the effect is enhanced with increasing dose. IFN-alpha and ATRA have no synergistic effect according to in vivo and in vitro test. ATRA has no effect on recurrence and metastasis of HCC.

Animals↗